Z28.20 — Immunization not carried out because of patient decision for unspecified reason
Is Z28.20 billable?
Yes, but Z28.20 is an unspecified code. Z28.20 is a valid, billable ICD-10-CM code for encounters from October 1, 2026 through September 30, 2027. However, Z28.20 is an unspecified or catch-all code. Payers apply additional scrutiny to unspecified codes and many deny them when the medical record supports a more specific option, so check the documentation before selecting Z28.20 — the more specific alternatives are listed below.
Z28.20 at a glance
| Code | Z28.20 |
|---|---|
| Description | Immunization not carried out because of patient decision for unspecified reason |
| Billable | Yes |
| Code set | ICD-10-CM FY2027 |
| Valid for encounters | October 1, 2026 – September 30, 2027 |
What Medicare edits apply to Z28.20?
The Medicare Code Editor screens inpatient claims before they are grouped. These edits name Z28.20 directly.
CMS will reject this code as the principal diagnosis on an inpatient claim. It describes something other than the condition chiefly responsible for the admission.
Which MS-DRGs does Z28.20 group to?
Z28.20 sits in MDC 15 and helps define the logic of 1 MS-DRG (version 44, FY2027). Which one a stay actually groups to also depends on procedures and secondary diagnoses.
- 795Normal Newbornmedical
How is Z28.20 listed in the Alphabetic Index?
These are the routes through the Alphabetic Index that lead to Z28.20. They show the wording a clinician may have documented, which often differs from the Tabular description.
- Immunization › not done › because › unspecified patient reason
Code also — inherited from Z28
Two codes may be needed to describe the condition fully. Whether Z28.20 is sequenced first depends on the reason for the encounter.
- , if applicable, encounter for immunization safety counseling (Z71.85)
How long has Z28.20 existed?
Z28.20 has been in ICD-10-CM since at least FY2016, the earliest fiscal year on record here.
Derived from the official order files for FY2016–FY2026. FY2017 and FY2020 publish no order file, so those years are not covered.